Bulk nickel-phosphorus-boron glasses bearing molybdenum

ABSTRACT

The disclosure provides Ni—Mo—P—B, Ni—Mo—Nb—P—B, and Ni—Mo—Nb—Mn—P—B alloys capable of forming metallic glass objects. The metallic glass objects can have lateral dimensions in excess of 1 mm and as large as 3 mm or larger. The disclosure also provides methods for forming the metallic glasses.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication No. 61/710,964, entitled “Bulk Nickel-Phosphorus-BoronGlasses Bearing Molybdenum”, filed on Oct. 8, 2012, and U.S. ProvisionalPatent Application No. 61/847,955, entitled “BulkNickel-Phosphorus-Boron Glasses Bearing Molybdenum, Niobium andManganese”, filed on Jul. 18, 2013, both of which are incorporatedherein by reference in their entirety.

TECHNICAL FIELD

The present disclosure is directed to nickel-phosphorus-boron (Ni—P—B)alloys bearing molybdenum (Mo) and optionally niobium (Nb) capable offorming bulk glassy rods with diameters of 1 mm or greater. The presentdisclosure is also directed to Ni—P—B alloys bearing Mo, Nb, and Mncapable of forming bulk metallic glass rods with diameters of at least1.5 mm and as large as 3 mm or greater.

BACKGROUND

Bulk glass forming Ni_(80.5-x)A_(x)P_(16.5)B₃ alloys, where element A isdefined as the combination of Cr and Nb, have recently been disclosed inU.S. patent application Ser. No. 13/592,095, entitled “Bulk Nickel-BasedChromium and Phosphorus Bearing Metallic Glasses”, filed on Aug. 22,2012. In those alloys, Cr ranges between 2 and 12 and Nb between 2 and4. The alloys of the present disclosure are represented by the samecompositional formula, but with A being instead a combination of Mo, Nb,and Mn, over approximately the same ranges.

Due to the attractive engineering properties of Ni-based P and B bearingbulk glasses, such as high strength, toughness, bending ductility, andcorrosion resistance, it is desirable to develop other families of suchalloys that incorporate different transition metals in order to explorethe possibility of even better engineering performance. These and otherneeds are accomplished by the descriptions in the present disclosure.

BRIEF SUMMARY

This disclosure provides bulk glass forming Ni—Mo—Nb—P—B alloys capableof forming a bulk metallic glass rod with a diameter of 3 mm. Such bulkmetallic glass rods can be formed when the molten alloy is processed bywater quenching while contained in a fused silica tube having a wallthickness not larger than 0.3 mm.

This disclosure further provides Ni—Mo—Nb—P—B alloys that can include asmall fraction of Mn. These alloys have better glass forming abilitycompared to the alloys free of Mn. Ni—Mo—Nb—Mn—P—B alloys are capable offorming metallic glass rods with diameters of at least 2 mm, and aslarge as 3 mm or larger when processed by melt water quenching in fusedsilica tubes having wall thickness of 0.5 mm. In addition, the metallicglasses have high yield strength and high notch toughness.

The disclosure is directed to an alloy or a metallic glass comprising analloy represented by the following formula (subscripts denote atomicpercent):

Ni(100-a-b-c-d)MoaNbbPcBd   Equation (1)

-   -   where:    -   a is between 2 and 12,    -   b is up to 8,    -   c is between 14 and 19, and    -   d is between 1 and 4.

In another embodiment, a+b is between 7 and 9.

In yet another embodiment, a is between 3 and 5 and b is between 3 and5.

In yet another embodiment, c+d is between 18.5 and 20.5.

In yet another embodiment, c is between 16 and 17 and d is between 2.75and 3.75.

In yet another embodiment, up to 1 atomic % of P is substituted by Si.

In yet another embodiment, up to 2 atomic % of Mo is substituted by Fe,Co, Mn, W, Cr, Ru, Re, Cu, Pd, Pt, V, Ta, or combinations thereof.

In yet another embodiment, up to 2 atomic % of Ni is substituted by Fe,Co, Mn, W, Cr, Ru, Re, Cu, Pd, Pt, V, Ta, or combinations thereof.

In yet another embodiment, the alloys are capable of forming amorphousrods of diameter of at least 1 mm when rapidly quenched from the moltenstate.

In yet another embodiment, the melt of the alloy is fluxed with areducing agent prior to rapid quenching.

In yet another embodiment, the temperature of the alloy melt prior toquenching is at least 100 degrees above the liquidus temperature of thealloy.

In yet another embodiment, the temperature of the alloy melt prior toquenching is at least 1100° C.

In yet another embodiment, rapid quenching is achieved bywater-quenching a quartz tube containing the molten alloy.

In yet another embodiment, the thickness of the quartz-tube wall isbetween 0.1 and 0.5 mm.

In yet another embodiment, a wire made of the metallic glass having adiameter of 1 mm can undergo macroscopic plastic bending under loadwithout fracturing catastrophically.

The disclosure is also directed to alloy or metallic glassNi_(72.8)Mo₄Nb₄P_(16.08)B_(3.12), Ni_(72.3)Mo₈P_(16.5)B_(3.2),Ni_(72.3)Mo₄Nb₄P_(16.5)B_(3.2),Ni_(72.3)Mo_(3.5)Nb_(4.5)P_(16.5)B_(3.2),Ni_(72.3)Mo₄Nb₄P_(16.2)B_(3.5), Ni_(72.3)Mo₃Nb₅P_(16.5)B_(3.2),Ni_(72.3)Mo_(4.5)Nb_(3.5)P_(16.5)B_(3.2),Ni_(72.3)Mo₅Nb₃P_(16.5)B_(3.2), Ni_(72.3)Mo₄Nb₄P_(17.2)B_(2.5), andNi_(72.3)Mo₄Nb₄P_(16.7)B₃.

In yet another embodiment, a method is provided for forming a metallicglass article. The method includes melting an alloy comprising at leastNi, Mo, P, and B and optionally Nb with a formulaNi_((100-a-b-c-d))Mo_(a)Nb_(b)P_(c)B_(d), where an atomic percent ofmolybdenum (Mo) a is between 2 and 12, an atomic percent of niobium (Nb)b is between 0 and 8, an atomic percent of phosphorus (P) c is between14 and 19, an atomic percent of boron (B) d is between 1 and 4, and thebalance is nickel (Ni). The method also includes quenching the moltenalloy at a cooling rate sufficiently rapid to prevent crystallization ofthe alloy.

The disclosure is directed to an alloy, or a metallic glass comprisingan alloy, represented by the following formula (subscripts denote atomicpercent):

Ni(100-a-b-c-d-e)MoaNbbMncPdBe   Equation (2)

where:

-   -   a is between 1 and 5,    -   b is between 3 and 5,    -   c is up to 2,    -   d is between 16 and 17, and    -   e is between 2.75 and 3.75,

In some embodiments, the largest rod diameter of the metallic glassaccording to Eq. (2) that can be formed when processed by waterquenching the high temperature melt in a fused silica tube having wallthickness of 0.5 mm is at least 1.5 mm.

In another embodiment, a+c of the alloy or metallic glass according toEq. (2) is between 3 and 5, while c is between 0.5 and 1.5, and whereinthe largest rod diameter that can be formed with an amorphous phase isat least 2 mm.

In another embodiment, a+c of the alloy or metallic glass according toEq. (2) is between 3.5 and 4.5, while c is between 0.75 and 1.25, andwherein the largest rod diameter that can be formed with an amorphousphase is at least 2.5 mm.

In yet another embodiment, up to 1 atomic percent of P of the alloy ormetallic glass according to Eq. (2) is substituted by Si.

In yet another embodiment, up to 2 atomic percent of Ni of the alloy ormetallic glass according to Eq. (2) is substituted by Fe, Co, W, Ru, Re,Cu, Pd, Pt, or combinations thereof.

In yet another embodiment, the melt of the alloy according to Eq. (2) isfluxed with a reducing agent prior to rapid quenching.

In yet another embodiment, the temperature of the alloy melt accordingto Eq. (2) prior to quenching is at least 200° C. above the liquidustemperature.

In yet another embodiment, the temperature of the alloy melt accordingto Eq. (2) prior to quenching is at least 1200° C.

In yet another embodiment, the compressive yield strength of themetallic glass according to Eq. (2) is at least 2200 MPa.

In yet another embodiment, the stress intensity at crack initiation(i.e. the notch toughness) of the metallic glass according to Eq. (2)when measured on a 2 mm diameter rod containing a notch with lengthbetween 0.75 and 1.25 mm and root radius between 0.1 and 0.15 mm is atleast 60 MPa m^(1/2).

In yet another embodiment, a wire made of such metallic glass accordingto Eq. (2) having a diameter of 1 mm can undergo macroscopic plasticdeformation under bending load without fracturing catastrophically.

The disclosure is also directed to an alloy, or a metallic glasscomprising an alloy, selected fromNi_(72.3)Mo_(3.5)Nb₄Mn_(0.5)P_(16.5)B_(3.2),Ni_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2), andNi_(72.3)Mo_(2.5)Nb₄Mn_(1.5)P_(16.5)B_(3.2).

Additional embodiments and features are set forth in part in thedescription that follows, and in part will become apparent to thoseskilled in the art upon examination of the specification or may belearned by the practice of the invention. A further understanding of thenature and advantages of the present invention may be realized byreference to the remaining portions of the specification and thedrawings, which forms a part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The description will be more fully understood with reference to thefollowing figures and data graphs, which are presented as variousembodiments of the disclosure and should not be construed as a completerecitation of the scope of the disclosure, wherein:

FIG. 1 provides a data graph showing the effect of Mo atomicconcentration on the glass forming ability of the Ni—Mo—P—B alloys.

FIG. 2 provides a data graph showing calorimetry scans for sampleNi—Mo—P—B metallic glasses from Table 1 with varying Mo atomicconcentration (Arrows from left to right designate the glass-transitionand liquidus temperatures).

FIG. 3 provides a data graph showing the effect of Nb atomicconcentration on the glass forming ability of the Ni—Mo—Nb—P—B alloys.

FIG. 4 provides an X-ray diffractogram verifying the amorphous structureof a 2.9 mm rod of sample metallic glass Ni_(72.3)Mo₄Nb₄P_(16.5)B_(3.2).

FIG. 5 provides a data graph showing calorimetry scans for sampleNi—Mo—Nb—P—B metallic glasses with varying Nb atomic concentration.Arrows designate the liquidus temperatures.

FIG. 6 provides a data graph showing the effect of B atomicconcentration on the glass forming ability of the Ni—Mo—Nb—P—B alloys.

FIG. 7 provides a data graph showing the calorimetry scans for sampleNi—Mo—Nb—P—B metallic glasses with varying B atomic concentration.Arrows designate the liquidus temperatures.

FIG. 8 provides a data graph showing the effect of metalloid atomicconcentration on the glass forming ability of the Ni—Mo—Nb—P—B alloys.

FIG. 9 provides an image showing a plastically bent 1 mm amorphous rodof sample metallic glass Ni_(72.3)Mo₅Nb₃P_(16.5)B_(3.2).

FIG. 10 provides a plot showing the effect of substituting Mo by Mn onthe glass forming ability of alloyNi_(72.3)Mo_(4-x)Nb₄Mn_(x)P_(16.5)B_(3.2).

FIG. 11 provides a plot showing calorimetry scans for sample metallicglass Ni_(72.3)Mo_(4-x)Nb₄Mn_(x)P_(16.5)B_(3.2). Arrows from left toright designate the glass-transition and liquidus temperatures,respectively.

FIG. 12 provides an optical image of an amorphous 3 mm rod of examplemetallic glass Ni_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2).

FIG. 13 provides an X-ray diffractogram verifying the amorphousstructure of a 3 mm rod of example metallic glassNi_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2).

FIG. 14 provides a compressive stress-strain diagram for sample metallicglass Ni_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2).

FIG. 15 provides an optical image of a plastically bent 1 mm metallicglass rod of sample metallic glass Ni_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2).

FIG. 16 provides a plot showing the corrosion depth versus time in 6MHCl solution of a 2 mm metallic glass rod having compositionNi_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2).

DETAILED DESCRIPTION

The present disclosure may be understood by reference to the followingdetailed description, taken in conjunction with the drawings asdescribed below. It is noted that, for purposes of illustrative clarity,certain elements in various drawings may not be drawn to scale.

Description of Alloy Compositions

Embodiments described herein may provide Ni—Mo—P—B, Ni—Mo—Nb—P—B, orNi—Mo—Nb—Mn—P—B alloys. The alloys are capable of forming bulk glassyrods with diameters of 1 mm or greater. In the current disclosure, ithas been discovered that the addition of Mo substituting Ni andoptionally the addition of Nb substituting Mo in the disclosed rangespromote bulk-glass formation in Ni—P—B alloys. In particular, the Nbcontaining Ni—Mo—Nb—P—B alloys have better glass forming ability thanthe Ni—Mo—P—B alloys. The relative B and P contents affect the glassforming ability (GFA), as does the total metalloid content in relationto the total metal content. Furthermore, the addition of Mn substitutingMo further promotes bulk-glass formation in Ni—Mo—Nb—P—B alloys. The Mncontaining Ni—Mo—Nb—Mn—P—B alloys have better glass forming ability thanthe Ni—Mo—Nb—P—B alloys. Additionally, glassy rods of sample metallicglasses with diameters up to 1 mm can be plastically bent.

In general, the glass-forming ability of each alloy may be assessed bydetermining the maximum or “critical” rod diameter in which theamorphous phase can be formed when processed by the method describedherein, which is, water quenching the molten alloy in quartzcapillaries. Since quartz is known to retard heat transfer, the quartzthickness is a critical parameter associated with the glass-formingability of the sample alloys. Therefore, to quantify the glass-formingability of each of the sample alloys, the critical rod diameter, d_(c),is reported in conjunction with the associated quartz thickness, t_(w),of the capillary used to process the alloy.

Ni—Mo—P—B and Ni—Mo—Nb—P—B Alloys and Metallic Glasses

Quartz capillaries with wall thicknesses that were about 10% of the tubeinner diameter were used for processing the sample Ni—Mo—Nb—P—B alloys.Table 1 shows sample Ni—Mo—P—B and Ni—Mo—Nb—P—B metallic glasses thatsatisfy the disclosed metallic glass composition formula, Eq. (1), alongwith the associated glass forming ability and corresponding tube wallthickness.

TABLE 1 Sample metallic glasses Ni—Mo—P—B and Ni—Mo—Nb—P—B compositionsand the associated glass forming ability of the corresponding glassforming alloys Sample Composition [at %] d_(c) [mm] t_(w) [mm] 1Ni_(77.3)Mo₃P_(16.5)B_(3.2) 0.6 0.06 2 Ni_(74.3)Mo₆P_(16.5)B_(3.2) 0.90.09 3 Ni_(73.3)Mo₇P_(16.5)B_(3.2) 1.0 0.1 4Ni_(72.8)Mo_(7.5)P_(16.5)B_(3.2) 1.5 0.15 5 Ni_(72.3)Mo₈P_(16.5)B_(3.2)1.2 0.12 6 Ni_(71.8)Mo_(8.5)P_(16.5)B_(3.2) 0.3 0.03 7Ni_(71.3)Mo₉P_(16.5)B_(3.2) 0.1 0.01 8 Ni_(72.3)Mo₇Nb₁P_(16.5)B_(3.2)1.3 0.13 9 Ni_(72.3)Mo₆Nb₂P_(16.5)B_(3.2) 2.0 0.2 10Ni_(72.3)Mo₅Nb₃P_(16.5)B_(3.2) 2.1 0.21 11Ni_(72.3)Mo_(4.5)Nb_(3.5)P_(16.5)B_(3.2) 2.2 0.22 12Ni_(72.3)Mo₄Nb₄P_(16.5)B_(3.2) 2.9 0.29 13Ni_(72.3)Mo_(3.5)Nb_(4.5)P_(16.5)B_(3.2) 2.4 0.24 14Ni_(72.3)Mo₃Nb₅P_(16.5)B_(3.2) 2.3 0.23 15Ni_(72.3)Mo₂Nb₆P_(16.5)B_(3.2) 1.6 0.16 16Ni_(72.3)Mo₄Nb₄P_(18.2)B_(1.5) 1.8 0.18 17 Ni_(72.3)Mo₄Nb₄P_(17.7)B₂ 2.00.2 18 Ni_(72.3)Mo₄Nb₄P_(17.2)B_(2.5) 2.1 0.21 19Ni_(72.3)Mo₄Nb₄P_(16.7)B₃ 2.1 0.21 20 Ni_(72.3)Mo₄Nb₄P_(16.2)B_(3.5) 2.70.27 21 Ni_(72.3)Mo₄Nb₄P_(15.95)B_(3.75) 1.7 0.17 22Ni_(72.3)Mo₄Nb₄P_(15.7)B₄ 1.1 0.11 23 Ni_(72.3)Mo₄Nb₄P_(15.2)B_(4.5) 0.50.05 24 Ni_(73.3)Mo₄Nb₄P_(15.66)B_(3.04) 1.9 0.19 25Ni_(72.8)Mo₄Nb₄P_(16.08)B_(3.12) 3.0 0.3 26Ni_(71.8)Mo₄Nb₄P_(16.92)B_(3.28) 2.0 0.2 27Ni_(71.3)Mo₄Nb₄P_(17.34)B_(3.36) 1.5 0.15 28Ni_(72.8)Mo_(3.5)Nb₄P_(16.5)B_(3.2) 2.4 0.24 29Ni_(72.8)Mo_(3.75)Nb_(3.75)P_(16.5)B_(3.2) 2.4 0.24 30Ni_(72.8)Mo₄Nb_(3.5)P_(16.5)B_(3.2) 2.3 0.23 31Ni_(72.3)Mo₄Nb₄P₁₆B_(3.2)Si_(0.5) 1.2 0.12 32Ni_(72.3)Mo₄Nb₄P_(15.5)B_(3.2)Si₁ 0.8 0.08

Substitution of Ni by Mo in Ni_(80.3)P_(16.5)B_(3.2) in the range of 3to 10 atomic percent was found to yield amorphous rods with diametersranging from 0.5 mm to greater than 1 mm. Samples 1-7 are Ni—Mo—P—Bmetallic glasses, in which the P and B contents are held constant whileNi is substituted by Mo, according to the formulaNi_(80.3-x)Mo_(x)P_(16.5)B_(3.2), where x denotes the Mo content. Ni wassubstituted by Mo in the range from 3% to 9%. Of these samples, sample 5reveals a peak in d_(c) of 1.5 mm at 7.5% Mo. The GFA data for samples1-7 are also presented graphically in FIG. 1.

FIG. 2 provides a data graph showing calorimetry scans for sampleNi—Mo—P—B metallic glasses (samples 1-6) from Table 1 with varying Moatomic concentration, according to the formulaNi_(80.3-x)Mo_(x)P_(16.5)B_(3.2)) where x denotes the Mo content. Thearrows from left to right designate the glass-transition and liquidustemperatures, respectively. Differential scanning calorimetry revealsthat increasing the Mo content raises the glass transition temperature,but does not substantially influence the liquidus temperatures. Lowerliquidus temperature, as illustrated in the calorimetry scan, implies animproved potential for glass-forming ability.

Samples 8-15 are Ni—Mo—Nb—P—B metallic glasses, in which the Ni, P, andB contents are held constant while Mo is substituted by Nb, according tothe formula Ni_(72.3)Mo_(8-x)Nb_(x)P_(16.5)B_(3.2), where x denotes theNb content. As shown, samples 8-15 have d_(c) ranging from 1.3 mm to 1.6mm, which is larger than the d_(c) values of 0.1 mm to 1.2 mm of samples1-7. In other words, further substitution of Mo by Nb inNi_(72.3)Mo₈P_(16.5)B_(3.2) in the range of 1 to 6 atomic percent wasfound to further improve the glass forming ability. Sample 12 has d_(c)of 2.9 mm such that the content of Mo and Nb are 4% for each. The GFAdata for samples 8-15 are presented graphically in FIG. 3.

The amorphous structure of a 2.9 mm diameter rod of metallic glassNi_(72.3)Mo₄Nb₄P_(16.5)B_(3.2) was verified by x-ray diffraction. FIG. 4provides an X-ray diffractogram revealing no sharp peaks, whichindicates absence of any crystals in the sample.

FIG. 5 provides a data graph showing calorimetry scans for samplemetallic glasses Ni—Mo—Nb—P—B with varying Nb atomic concentration(samples 8-15), according to the formulaNi_(72.3)Mo_(8-x)Nb_(x)P_(16.5)B_(3.2), where x denotes the Nb content.The arrows from left to right designate the glass-transition andliquidus temperatures, respectively. As shown, the glass transitiontemperatures of the metallic glasses do not change much with varying Nbcontent, but the liquidus temperatures change with varying Nb content.Therefore, the differential scanning calorimetry reveals that the Nbsubstitution does not substantially influence the glass transitiontemperature, but the melting behavior is considerably influenced, as theliquidus temperatures go through a minimum at about 3-4%, which is neara Nb content of 4%. Again, lower liquidus temperature as illustrated inthe calorimetry scan implies an improved potential for glass-formingability.

Samples 12 and 16-23 are also metallic glasses Ni—Mo—Nb—P—B in which theNi, Mo, Nb contents are held constant while P is substituted by B,according to the formula Ni_(72.3)Mo₄Nb₄P_(19.7-x)B_(x), where x denotesthe B content. Out of these samples, sample 12 shows a peak in d_(c) of2.9 mm at B content of 3.2%. The GFA data for samples 12 and 16-23 arepresented graphically in FIG. 6.

FIG. 7 provides a data graph showing the calorimetry scans for samplemetallic glasses Ni—Mo—Nb—P—B with varying B atomic concentrationaccording to the formula Ni_(72.3)Mo₄Nb₄P_(19.7-x)B_(x), where x denotesthe B content (samples 17, 19, 20, and 22). The arrows from left toright designate the glass-transition and liquidus temperatures,respectively. As shown, the glass transition temperature of the metallicglasses is not greatly affected by varying the B content. However, thedifferential scanning calorimetry reveals that the liquidus temperaturegoes through a minimum near the B content of 3%. Again, lower liquidustemperature, as illustrated in the calorimetry scan, implies an improvedpotential for glass-forming ability.

Samples 12 and 24-27 are also Ni—Mo—Nb—P—B metallic glasses in which theMo and Nb content is held constant while the total metalloid content isvaried with the Ni content according to the formulaNi_(92-x)Mo₄Nb₄(P_(0.8376)B₁₆₂₄)_(x), where x denotes the B content.Shifting the metalloid content in the alloy is shown to influenceglass-forming ability. Out of these samples, sample 25 shows a peakd_(c) in of 3.0 mm at metalloid content of 19.2% B. This GFA data ispresented graphically in FIG. 8.

Samples 28-30 are also Ni—Mo—Nb—P—B metallic glasses, in which the Ni, Pand B content is held constant while Mo is substituted by Nb, accordingto the formula Ni_(72.8)Mo_(7.5-x)Nb_(x)P_(16.5)B_(3.2), where x denotesthe Nb content. This GFA data shows that substitution of Mo by Nb whenthe total Mo and Nb content is 7.5 instead of 8 does not offer anyimprovement in GFA.

Samples 30-31 are Ni—Mo—Nb—P—B—Si metallic glasses in which the Ni, Mo,Nb, and B content is held constant while P is substituted by Si,according to the formula Ni_(72.3)Mo₄Nb₄P_(16.5-x)B_(3.2)Si_(x), where xdenotes the Si content. This GFA data reveals that when P is substitutedby Si, d_(c) decreases.

The metallic glasses of Eq. (1) were found to exhibit a bendingductility. Specifically, under an applied bending load, the disclosedmetallic glasses of Eq. (1) were capable of undergoing plastic bendingin the absence of fracture for diameters up to 1 mm. FIG. 9 provides animage showing a plastically bent 1 mm amorphous rod of sample metallicglass Ni_(72.3)Mo₅Nb₃P_(16.5)B_(3.2). This demonstrates that themetallic glass Ni_(72.3)Mo₅Nb₃P_(16.5)B_(3.2) rod of 1 mm diameter isable to undergo macroscopic plastic bending under load withoutfracturing catastrophically.

Ni—Mo—Nb—Mn—P—B Alloys and Metallic Glasses

When a small fraction of Mn of up to 2 atomic percent substitutes Mo ina Ni—Mo—Nb—P—B alloy, the glass forming ability of the alloy isenhanced. The critical rod diameter determined by processing in fusedsilica with a wall thickness of 0.5 mm is increased from about 1 mm forthe Mn-free alloy to about 3 mm or more. In one embodiment, theNi—Mo—Nb—P—B composition includes about 4 atomic percent Mo, about 4atomic percent Nb, between 16 and 17 atomic percent P, between 3 and 3.5atomic percent B, and the balance is Ni. An atomic percent of Mn between0.5 and 1.5 substitutes Mo in this Ni—Mo—Nb—P—B composition.

Sample metallic glasses (Samples 12, 33-35) showing the effect ofsubstituting Mo by Mn. Metallic glasses having the formulaNi_(72.3)Mo_(4-x)Nb₄Mn_(x)P_(16.5)B_(3.2), are presented in Table 2 andFIG. 10. When the Mn atomic percent is between 0.5 and 1.5, metallicglass rods with diameters greater than 2 mm can be formed. When the Mnatomic percent is at about 1, 3-mm diameter metallic glass rods can beformed. Differential calorimetry scans for sample metallic glasses inwhich Mo is substituted by Mn are presented in FIG. 11.

TABLE 2 Sample metallic glasses demonstrating the effect of substitutingMo by Mn on the glass forming ability of the Ni—Mo—Nb—P—B alloysCritical Rod Sample Composition Diameter [mm] 12Ni_(72.3)Mo₄Nb₄P_(16.5)B_(3.2) 1 33Ni_(72.3)Mo_(3.75)Nb₄Mn_(0.25)P_(16.5)B_(3.2) 1.5 34Ni_(72.3)Mo_(3.5)Nb₄Mn_(0.5)P_(16.5)B_(3.2) 2 35Ni_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2) 3 36Ni_(72.3)Mo_(2.5)Nb₄Mn_(1.5)P_(16.5)B_(3.2) 2 37Ni_(72.3)Mo_(2.25)Nb₄Mn_(1.75)P_(16.5)B_(3.2) 1.5 38Ni_(72.3)Mo₂Nb₄Mn₂P_(16.5)B_(3.2) <1.5

Among the prepared compositions, the alloy exhibiting the highestglass-forming ability is Sample 35 (Ni_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2)).The alloy is capable of forming metallic glass rods of up to 3 mm indiameter. An image of a 3 mm diameter metallic glass rod having thecomposition Ni_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2) rod is shown in FIG. 12.An x-ray diffractogram taken on the cross section of a 3 mm diameterNi_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2) rod verifying its amorphous structureis shown in FIG. 13.

Various mechanical properties of the Ni_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2)metallic glass were investigated. The measured mechanical propertiesinclude compressive yield strength, notch toughness, bending ductility,and hardness.

The compressive yield strength, σ_(y), is the measure of the material'sability to resist non-elastic yielding. The yield strength is the stressat which the material yields plastically. A high σ_(y) ensures that thematerial will be strong.

The stress intensity factor at crack initiation (i.e. the notchtoughness), K_(q), is the measure of the material's ability to resistfracture in the presence of a notch. The notch toughness is a measure ofthe work required to propagate a crack originating from a notch. A highK_(q) ensures that the material will be tough in the presence ofdefects.

Bending ductility is a measure of the material's ability to deformplastically and resist fracture in bending in the absence of a notch ora pre-crack. A high bending ductility ensures that the material will beductile in a bending overload.

Hardness is a measure of the material's ability to resist plasticindentation. A high hardness will ensure that the material will beresistant to indentation and scratching.

These four properties characterize the material's mechanical performanceunder stress.

A plastic zone radius, r_(p), defined as K_(p) ²/πσ_(y) ², is a measureof the critical flaw size at which catastrophic fracture is promoted.The plastic zone radius determines the sensitivity of the material toflaws; a high r_(p) designates a low sensitivity of the material toflaws.

A list of measured properties for the sample metallic glassNi_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2) (Sample 35) is presented in Table 3.The stress-strain diagram for sample metallic glassNi_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2) is presented in FIG. 14.

TABLE 3 Measured properties of metallic glassNi_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2). CompositionNi_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2) Critical rod diameter 3 mmGlass-transition temperature 408° C. Crystallization temperature 448° C.Solidus temperature 832° C. Liquidus temperature 904° C. Density 8.06g/cc Yield strength 2430 MPa Hardness 673.5 ± 6.8 kgf/mm² Notchtoughness 72.6 ± 2.4 MPa m^(1/2)

The metallic glasses according to Eq. (2) demonstrate bending ductility.Specifically, under an applied bending load, the metallic glasses arecapable of undergoing plastic bending in the absence of fracture fordiameters up to at least 1 mm. An optical image of a plastically bentamorphous rod at 1-mm diameter section of example metallic glassNi_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2) is presented in FIG. 15.

Lastly, the metallic glasses Ni—Mo Nb—Mn—P—B also exhibit a corrosionresistance. The corrosion resistance of example metallic glassNi_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2) is evaluated by immersion test in 6MHCl. A plot of the corrosion depth versus time is presented in FIG. 16.The corrosion depth at approximately 673 hours is measured to be about4.7 micrometers. The corrosion rate is estimated to be 0.068 mm/year.The corrosion rate of all metallic glasses according to the currentdisclosure is expected to be under 1 mm/year.

Methods of Processing Sample Alloys

The alloys or alloy ingots can be produced by inductive melting of theelemental constituents in a quartz tube (i.e. fused silica tubes) underan inert atmosphere. The purity levels of the constituent elements wereNi 99.995%, Mo 99.95%, Nb 99.95%, Mn 99.9998%, P 99.9999%, and B 99.5%.The melting crucible may alternatively be a ceramic such as alumina orzirconia, graphite, or a water-cooled hearth made of copper or silver.

Metallic glass rods can be produced from the alloy ingots by re-meltingthe alloy ingots in quartz tubes in a furnace at 1100° C. or higher,e.g. between 1200° C. and 1400° C., under inert atmosphere, e.g. underhigh purity argon. Subsequently, the quartz tube containing the alloymelt can be rapidly quenched in a room-temperature water bath.Alternatively, the bath could be iced water or oil. Metallic glassarticles in general can be alternatively formed by injecting or pouringthe molten alloy into a metal mold. The mold can be made of copper,brass, or steel, among other materials.

In preparing the metallic glass rods in the present disclosure, the wallthickness of the quartz tubes ranged from 0.06 mm to 0.5 mm. Fusedsilica is generally a poor thermal conductor. Slightly increasing thethickness of the tube wall slows the heat removal rate during the meltquenching process, thereby limiting the diameter of a rod that can beformed with an amorphous phase by a given composition. For example, thealloy Ni_(72.3)Mo₄Nb₄P_(16.5)B_(3.2) is capable of forming amorphous 3mm diameter rods (Sample 12 in Table 1) when processed by waterquenching the high temperature melt in a fused silica tube having wallthickness of 0.3 mm. When processed in the same manner in a fused silicatube having wall thickness of 0.5 mm, the alloyNi_(72.3)Mo₄Nb₄P_(16.5)B_(3.2) is capable of forming metallic glass rodsof only 1 mm in diameter.

Optionally, prior to producing an amorphous article, the alloy ingotscan be fluxed with a reducing agent. The ingots can be remelted in aquartz tube under inert atmosphere along with a reducing (fluxing)agent. Then, the alloy melt can be brought in contact with the moltenreducing agent to allow the two melts to interact for about a timeperiod of at least 1000 seconds (e.g. between 1 and 12 hours) at atemperature of about 1100° C. or higher (e.g. between 1200° C. and 1400°C.), and the alloy melt can be subsequently cooled by water quenching.

Test Methodology for Differential Scanning Calorimetry

Differential scanning calorimetry was performed on sample metallicglasses at a scan rate of 20 K/min to determine the glass-transition,crystallization, solidus, and liquidus temperatures of sample metallicglasses.

Test Methodology for Assessing Glass-Forming Ability

The glass-forming ability of each alloy was assessed by determining themaximum rod diameter in which the amorphous phase of the alloy (i.e. themetallic glass phase) can be formed when processed by the methoddescribed above. X-ray diffraction with Cu—Kα radiation was performed toverify the amorphous structure of the alloys.

Test Methodology for Measuring Notch Toughness

The notch toughness of sample metallic glasses was performed on 2-mmdiameter rods. The rods were notched using a wire saw with a root radiusof between 0.10 and 0.13 μm to a depth of approximately half the roddiameter. The notched specimens were placed on a 3-point bending fixturewith span distance of 12.7 mm and carefully aligned with the notchedside facing downward. The critical fracture load was measured byapplying a monotonically increasing load at constant cross-head speed of0.001 mm/s using a screw-driven testing frame. At least three tests wereperformed, and the variance between tests is included in the notchtoughness plots. The stress intensity factor for the geometricalconfiguration employed here was evaluated using the analysis by Murakimi(Y. Murakami, Stress Intensity Factors Handbook, Vol. 2, Oxford:Pergamon Press, p. 666 (1987)).

Test Methodology for Measuring Compressive Yield Strength

Compression testing of sample metallic glasses was performed oncylindrical specimens 2 mm in diameter and 4 mm in length. Amonotonically increasing load was applied at a constant cross-head speedof 0.001 mm/s using a screw-driven testing frame. The strain wasmeasured using a linear variable differential transformer. Thecompressive yield strength was estimated using the 0.2% proof stresscriterion.

Test Methodology for Measuring Hardness

The Vickers hardness (HV0.5) of sample metallic glasses was measuredusing a Vickers microhardness tester. Nine tests were performed wheremicro-indentions were inserted on a flat and polished cross section of a2 mm metallic glass rod using a load of 500 g and a duel time of 10 s.

Test Methodology for Measuring Corrosion Resistance

The corrosion resistance of sample metallic glasses was evaluated byimmersion tests in hydrochloric acid (HCl). A rod of metallic glasssample with initial diameter of 1.99 mm, and a length of 22.55 mm wasimmersed in a bath of 6M HCl at room temperature. The density of themetallic glass rod was measured using the Archimedes method. Thecorrosion depth at various stages during the immersion was estimated bymeasuring the mass change with an accuracy of ±0.01 mg. The corrosionrate was estimated assuming linear kinetics.

The disclosed Ni—Mo—P—B, Ni—Mo—Nb—P—B, or Ni—Mo—Nb—Mn—P—B alloys withcontrolled ranges of Mo, Nb, Mn, and metalloids P and B have good glassforming ability, as they are capable of forming bulk metallic glass rodswith diameters as large as 3 mm or larger. The metallic glasses formedfrom the alloys also demonstrate high strength, hardness, toughness,bending ductility, and corrosion resistance.

The combination of high glass-forming ability and the mechanical andcorrosion performance of the bulk Ni-based metallic glasses make themcandidates for various applications. For example, the disclosed alloysmay be used in applications such as consumer electronics, dental andmedical implants and instruments, luxury goods, and sporting goods,among many other applications.

Having described several embodiments, it will be recognized by thoseskilled in the art that various modifications, alternativeconstructions, and equivalents may be used without departing from thespirit of the invention. Additionally, a number of well-known processesand elements have not been described in order to avoid unnecessarilyobscuring the present invention. Accordingly, the above descriptionshould not be taken as limiting the scope of the invention.

Those skilled in the art will appreciate that the presently disclosedembodiments teach by way of example and not by limitation. Therefore,the matter contained in the above description or shown in theaccompanying drawings should be interpreted as illustrative and not in alimiting sense. The following claims are intended to cover all genericand specific features described herein, as well as all statements of thescope of the present method and system, which, as a matter of language,might be said to fall therebetween.

What is claimed is:
 1. An alloy comprising:Ni_((100-a-b-c-d))Mo_(a)Nb_(b)P_(c)B_(d) wherein subscripts a, b, c, andd, denote atomic percents for Mo, Nb, P, and B, respectively, wherein ais between 2 and 12, b is up to 8, c is between 14 and 19, d is between1 and 4, and the balance is nickel (Ni), and wherein the alloy iscapable of forming an object comprising a metallic glass.
 2. The alloyof claim 1, wherein a combined atomic percent of Mo and niobium isbetween 7 and
 9. 3. The alloy of claim 1, wherein the atomic percent ofMo is between 3 and 5, and the atomic percent of Nb is between 3 and 5.4. The alloy of claim 1, wherein a combined atomic percent of P and B isbetween 18.5 and 20.5.
 5. The alloy of claim 1, wherein the atomicpercent of P is between 16 and 17, and the atomic percent of B isbetween 2.75 and 3.75.
 6. The alloy of claim 1, wherein up to 1 atomicpercent of P is substituted by Si.
 7. The alloy of claim 1, wherein upto 2 atomic % of Mo or Ni is substituted by Fe, Co, Mn, W, Cr, Ru, Re,Cu, Pd, Pt, V, Ta, or combinations thereof.
 8. The alloy of claim 1,wherein the alloy is selected from a group consisting ofNi_(72.8)Mo₄Nb₄P_(16.08)B_(3.12), Ni_(72.3)Mo₈P_(16.5)B_(3.2),Ni_(72.3)Mo₄Nb₄P_(16.5)B_(3.2),Ni_(72.3)Mo_(3.5)Nb_(4.5)P_(16.5)B_(3.2),Ni_(72.3)Mo₄Nb₄P_(16.2)B_(3.5), Ni_(72.3)Mo₃Nb₅P_(16.5)B_(3.2),Ni_(72.3)Mo_(4.5)Nb_(3.5)P_(16.5)B_(3.2),Ni_(72.3)Mo₅Nb₃P_(16.5)B_(3.2), Ni_(72.3)Mo₄Nb₄P_(17.2)B_(2.5), andNi_(72.3)Mo₄Nb₄P_(16.7)B₃.
 9. The alloy of claim 1, wherein the alloy iscapable of forming an object comprising a metallic glass having alateral dimension of at least 1 mm.
 10. An alloy comprising:Ni_((100-a-b-c-d-e))Mo_(a)Nb_(b)Mn_(c)P_(d)B_(e), wherein subscripts a,b, c, d, and e denote atomic percents for Mo, Nb, Mn, P and B,respectively, a is between 1 and 5, b is between 3 and 5, c is up to 2,d is between 16 and 17, and e is between 2.75 and 3.75, wherein thealloy is capable of forming an object comprising a metallic glass havinga lateral dimension of at least 1.5 mm.
 11. The alloy of claim 10,wherein a combined atomic percent of Mo and Mn is between 3 and 5,wherein the atomic percent of manganese is between 0.5 and 1.5, andwherein the alloy is capable of forming an object comprising a metallicglass having a lateral dimension of at least 2 mm.
 12. The alloy ofclaim 11, wherein the combined atomic percent of Mo and Mn is between3.5 and 4.5, wherein the atomic percent of Mn is between 0.75 and 1.25,and wherein the alloy is capable of forming an object comprising ametallic glass having a lateral dimension of at least 2.5 mm.
 13. Thealloy of claim 10, wherein the alloy is selected from a group consistingof Ni_(72.3)Mo_(3.5)Nb₄Mn_(0.5)P_(16.5)B_(3.2),Ni_(72.3)Mo₃Nb₄Mn₁P_(16.5)B_(3.2), andNi_(72.3)Mo_(2.5)Nb₄Mn_(1.5)P_(16.5)B_(3.2).
 14. The alloy of claim 10,wherein up to 1 atomic percent of P is substituted by Si.
 15. The alloyof claim 10, wherein up to 2 atomic percent of Ni is substituted by Fe,Co, W, Ru, Re, Cu, Pd, Pt, or combinations thereof.
 16. A metallic glasscomprising the alloy of claim
 10. 17. The metallic glass of claim 16,wherein the stress intensity at crack initiation when measured on a 2 mmdiameter rod containing a notch with length between 0.75 and 1.25 mm androot radius between 0.1 and 0.15 mm is at least 60 MPa m^(1/2).
 18. Themetallic glass of claims 16, wherein a wire made of the metallic glasshaving a diameter of 1 mm can undergo macroscopic plastic deformationunder bending load without fracturing catastrophically.
 19. A method ofproducing the metallic glass of claim 16, the method comprising: meltingthe alloy; and quenching the molten alloy at a cooling rate sufficientlyrapid to prevent crystallization of the alloy.
 20. The method of claim19, further comprising fluxing the molten alloy prior to quenching byusing a reducing agent.